Invalidate GrTexture mipmap on content change notification

Invalidate GrTexture mipmap on content change notification

This fix is necessary to correctly propagate invalidations that
are external to skia. For example, when drawing video or WebGL
into a 2D canvas in Chrome, with mipmaps enabled.

BUG=crbug.com/498356
TEST=GrTextureMipMapInvalidationTest

Committed: https://skia.googlesource.com/skia/+/da5469d7bc0dc089d098f5a64a818ed079cc0930

[Justin Novosad, 2015-06-11 18:01:41]

junov@chromium.org changed reviewers:
+ bsalomon@google.com

[Justin Novosad, 2015-06-11 18:01:41]

PTAL

[Justin Novosad, 2015-06-11 18:02:06]

The CQ bit was checked by junov@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-06-11 18:02:19]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1177843007/1

[commit-bot: I haz the power, 2015-06-11 18:07:42]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-06-11 18:07:43]

Dry run: This issue passed the CQ dry run.

[bsalomon, 2015-06-11 18:14:42]

bsalomon@google.com changed reviewers:
+ reed@google.com

[bsalomon, 2015-06-11 18:14:42]

lgtm, but reed@ for change to SkPixelRef interface.

[Justin Novosad, 2015-06-15 14:04:24]

reed@: review ping.

[reed1, 2015-06-15 16:07:19]

lgtm

[Justin Novosad, 2015-06-15 16:42:29]

The CQ bit was checked by junov@chromium.org

[Justin Novosad, 2015-06-15 16:42:29]

The patchset sent to the CQ was uploaded after l-g-t-m from bsalomon@google.com
Link to the patchset: https://codereview.chromium.org/1177843007/#ps20001
(title: "typo fix")

[commit-bot: I haz the power, 2015-06-15 16:42:42]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1177843007/20001

[commit-bot: I haz the power, 2015-06-15 16:48:18]

Committed patchset #2 (id:20001) as
https://skia.googlesource.com/skia/+/da5469d7bc0dc089d098f5a64a818ed079cc0930